Fluid-tight light transmitting apparatus



Sept. 4, 1951 J. F. SHANNON FLUID-TIGl-l'l' LIGHT TRANSII'I'IING APPARATUS Filedl Aug. 26, 1948 9 3 z5/:: :5a. l l l I. m f. 4 s l /\h\l/\H\| son U r ..1 H n l l l l ..N 1 n .l m 2- l l INVENTOR.

JACK F. SHANNON NEY atented Sept. 4, 1951 FLUID-TIGHT LIGHT TRANSMITTING APPARATUS Jack F. Shannon, Euclid, Ohio, assigner to Bailey Meter Company, a corporation of Delaware Application August 28, 1948, Serial No. 46.249

l 3 Claims.

This invention relates to light sensitive systems and more particularly to apparatus for transmitting light from a pressure chamber to a light sensitive device spaced a substantial distance from the chamber.

In order to avoid furnace explosions, a light sensitive device, such as a phototube, is sometimes directed on the flame within the furnace and is connected in a circuit to control the operation of an alarm. As long as ignition is maintained in the furnace. light from the flame reacts on the phototube, causing it to have a low electrical resistance and thereby maintain a dow of current through a relay controlling an alarm circuit. In case of flame failure, light to the phototube is immediately reduced and the resistance of the phototube increases sharply. The ilow of current is then reduced so that the relay operates to close or open contacts for giving an alarm. In some cases, the light sensitive device may be directed on a heated object or material within a furnace and be connected in a circuit for controlling the operation of the furnace so as to maintain the temperature of the object or material at a desired value.

Regardless of the type of control circuit employed. it is necessary that the changes in the intensity of the light acting on the phototube be sufilciently great so that the change in current flow through the control circuit will provide the desired operation. It may be impossible in some cases to locate the phototube close enough to the source of light so that the light passing to it will affect its resistance appreciably. It may also be impossible to expose the photctube dircctly to the light from the source because of pressure difierences that must be maintained between them. If the pressure at the light source is very high compared to that at the phototube. and the distance between the source and the phototube is comparatively great. then means must be provided for picking up light rays from the source and concentrating them on the phototube. and the means must be adapted for engagement by sealing means to prevent the escape of pressure. At the same time. the light transmitting or concentrating means must be arranged for'removal so that it may be cleaned. when necessary.

An object of my invention is to provide an improved apparatus for transmitting light from s source to a light sensitive device. Another object is to provide improved means for transmltting light between points at diiierent pressuresandyetpreventingtheeeeapeofpressure from one point to another. Still another object is to provide improved apparatus for transmitting light from a sealed chamber under high pressure to a light sensitive device located at a substantial distance from the chamber. Yet another object is to provide improved means adapted to be sealed within an opening to a pressure chamber for transmitting light to a light sensitive device. and yet being removable for cleaning when necessary. Other objects will appear in the course of the following description.

In the accompanying drawing there is shown for purposes of illustration. one form which my invention may assume in practice.

In this drawing:

Fig. l is a schematic diagram showing my invention arranged for transmitting light from a heated chamber to a phototube connected in an alarm control circuit.

Fig. 2 is an enlarged sectional view of my improved light transmitting means.

Fig. 3 shows valve means for controlling communlcation between the heated chamber and the light transmitting means.

In Fig. l there is shown a chamber I arranged concentrically within a chamber 2 and having a burner 2 to which fuel is supplied at high pressure from a conduit l. Air or gases supporting combustion at the burner is supplied at high pressure from a suitable source, not shown. through a conduit l to the lower end ofthe chamber I. 'I'he products of combustion are discharged through passage means l which are adapted to maintain relatively high pressure within the chamber I. The chamber 2 may contain a cooling liquid. as shown, or it may contain a gaseous fluid at a pressure which is different from that at its exterior or that in the chamber I. This arrangement is shown because it requires that light from the burner llame be transmitted a considerable distance to a light sensitive device. such as a phototube I. locate. at the exterior of the chamber l for controlling an alarm l in response to changes in the intensity of the light. It also requires that the light transmitting means be sealed against the escape of pressure from the chamber I to the chamber 2 and to the atmosphere at the exterior oi the chamber 2. and that means be provided for holding it in place against the action of the pressure in chamber I. It will be appreciated that there may be other arrangements which require means for transmitting light considerable distances without passing through a chamber between the source and the light sensi-- tive device. and in which the pressure at the light source may be higher. lower, or the same as the pressures at different points along the transmitting means.

As shown in Fig. l, my improved light trans` mitting means, generally designated I0, includes a tubular member I I extending through an opening in the outer wall I2 of the chamber 2 and threaded at its inner end into a coupling Il secured within an opening in the wall It of the chamber I. The tubular member may be welded within the opening in the wall I2. if desired, to prevent the escape of uid from the chamber 2 to -the atmosphere. Threaded on the outer end of the tubular member, as shown in Fig. 2, is an annular member I1 having a projectingend portion I8 adapted to be received in a recess formed in the end of a coupling member I8. A collar is threaded on the member l1 and has an inwardly projecting nange portion 2| engageable with a fiange portion 22 on the member Il for moving the members I1 and I9 into fluid tight engagement with each other. A coupling member 24 has threaded connection with the member I8 and is provided with an opening threadedly receiving a reduced portion 28 of a member 21. Extending through the tubular member II and the members I1, I9, 24 and 21 is a rod 28 made of a transparent material. such as quartz,

for transmitting light from a poin. close to the chamber I to av point at -the outer end of the member 21. A- spring 28 is arranged between the tubular member and the rod for yieldingly supporting the latter in place. Arranged within the member 2l is a packing ring-80, and an annular member JI engages the outer face of the packing ring and is adapted to be forced bythe reduced portion 28 oi the member 21 against the packing for eilecting a sealing engagement by the latter with the rod 28 and with the member 2l. Formed in the end ofthe member 21 is a recess adapted to receive an annular member 32 engageable by the rod 28 for preventing longitudinal movement of the latter by pressure acting on its inner end. The member l2 may be held inv the recess by welding or by any suitable means attached to the member 21. If' desired, the member 21 may be provided with an integral portion to take the place of the member 32. Surrounding the member 21 is an annular member 85 held in place as by a screw 2t, and the member 2 5 is adapted to be received within the open end .of a chamber forming member 88, as shown in Fig. 1.`

When the intensity of the light in the chani ber I is high. the resistance of the phototube is low by reason of the light transmitted to it through the rod 28, Pd the current flow through the resistance II produces a voltage drop therein which causes the amplifier to energize therelay winding I8 for holding the contacter in its open position. A failure of the name within the chamber I results in a sharp increase in the resistance of the phototube and a reduction oi the voltage drop in the resistance 4l to a point where the ampliier no longer energizes the relay winding for holding the contactar 4l open. 'lhe circuit through the alarm is then completed to warn the attendant that attention is needed.

It is desirable that the chamber member I8 be moved away from the outer end of the rod 2o at times so that the operator may either look through the rod or remove it for cleaning its inner end. The member 2l is therefore slideably and pivotally supported on a member 85 carried at its ends by stationary supports 86. When the chamber device is moved clear of the member 35 it may be swung about the member to a position out of line with the light transmitting means l0. To remove the rod 28 for cleaning, the collar 20 is unscrewed from the member Il so that the rod with the members 24 and 28 still holding the packing clamped thereon, may be removed from the tubular member II. When the inner end of the rod has been cleaned. it may be reinserted in the tubular member. and the collar 20 screwed on the member I1 until the members I1 and Il again sealingly engage each other. If it is necessary that the rod be removed'for cleaning while the burner I is still operating, or when dltterent pressures exist in the chambers I and V2, a gate vvalve I8 may be arranged in the cou'- pling Il, as shown in Fig. 3, and a valve stem 59 4may be extended from the valve through the chamber 2 and the wall of the latter to a point where it may be operated manually for opening and closing the valve.

Incertain'installations it may be that temperature.' rather than pressure, is the principal reason for necessarily locating the phototube 8 at -some distance from the source of light. For in- The phototube 8 is arranged within -the chamstance, the wall It might be the enclosing or shielding wall of a billet heating furnace or ofl Y an open hearth furnace and of material thick ness. Insueh cases it is essential that the small- .est opening be made through the wall for sightlng on the heated metal' and. due tothe thickness of the wall and the heat within the furnace, it is not possible .for the phototube 8 to be located nearer than some considerable 4distance from the the member t8 and forms a light .tight seal. *The light sensitiveelements of the phototube are connected in a series circuit including a conductor 38, a resistance Il, a conductor l2, a source of Ds-C. power 4l, and a conductor Il. The -voltage drop across the resistance. is applied by conductors 48 and It to an ampliner 4 1, and the output of the amplifier is connected to a relay winding 48 which operates when sumciently energized to move a contactor u against ,the action of a spring l0 into engagement with a contact 8i. When the current through the relay winding is reduced to a point where it can no longer hold the contacter against the spring action. the contactor is moved into engagement with a contact 82 which is connected in s circuit including the alarm l, a source of power I3, such as a battery. and the contacter 48.

object to besighted. A

While thereis described in this application one .form which my invention may assume in practice.

it .will be understood thatit may be modliledand -in various otherforms without depart its 'spirit or'the scope ofthe appended '.'What Iclaim as new anddesire to secure by Letters Patent of the United States, is:

1.-Fluid-tight light transmitting apparatus.-

between a light source and a remote point in-t cluding, in combination, a tubular member conl nected fluid-tight by one end to the light source, a transparent rod through said tubular member and projecting from its other end, spring structure radially disposed about the rodinthe annular space formed with the tubular member. a coupling arranged labout theprojecting end nt Vthe rod in duid-tight engagement with the tubu-.

5 lar member, and a packing in uuid-tight engagement with the rod by reason of compression by a portion of the coupling.

2. Light transmitting apparatus between a source and a sensitive device including, in combination, a tubular member connected uidtight by one end to the light'source. a quartz rod extending through the tubular member and pro- `iecting from its other end, coupling members surrounding the projecting portion of said rod and holding a packing in iluid-tight engagement therewith, means for connecting one of the coupling members in duid-tight communication with the tubular member, an abutment structure carried by one of the coupling members enr aging the outer end extremity of the rod for preventing its movement against. the light sensitive. device beyond that end. and a chamber for the light sensitive device receiving the outer end ot the coupling members in a close sliding nt for ready disengagement.

3. Apparatus for transmitting light from a pressure chamber to a pointjspaced through a iluid medium including, in combination. a tubularv member extending through the uid, a manually adjustable valve means secured fluid-tight between a tubular member inner end and the pressure chamber, a transparent rod extending JACK F. SHANNON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 931,128 Keith Aug. 17, 1909 1,008,485 Megger Nov. 14, 1911 1,268,678- 'Gromann -1---- May 21, 1918 1,323,309 Northrup Dec. 2, 1919 1,351,562 Foster Aug. 3l, 1920 1,745,178 McCabe Jan. 28, 1930 1,800,277 Boerstler Apr. 14, 1931 1,875,048 Levene Aug. 30, 1932 1,883,971 Kryzanowsky Oct. 25, 1932 2,215,576 Bucknan et al Sept. 24, 1940 2,295,045 Mettler Sept. 8, 1942 2,337,535 Acs, Jr Dec. 28, 1943 2,382,251 Parker et al. Aug. 14. 1945 

